<!DOCTYPE html>
<html lang="en-us">
  <head>

    <meta http-equiv="content-type" content="text/html; charset=utf-8">
    
<meta charset="UTF-8">
<title>Stopwords and Performance | Elasticsearch: The Definitive Guide [2.x] | Elastic</title>
<link rel="home" href="index.html" title="Elasticsearch: The Definitive Guide [2.x]">
<link rel="up" href="stopwords.html" title="Stopwords: Performance Versus Precision">
<link rel="prev" href="using-stopwords.html" title="Using Stopwords">
<link rel="next" href="common-terms.html" title="Divide and Conquer">
<meta name="DC.type" content="Learn/Docs/Legacy/Elasticsearch/Definitive Guide/2.x">
<meta name="DC.subject" content="Elasticsearch">
<meta name="DC.identifier" content="2.x">
<meta name="robots" content="noindex,nofollow">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <script src="https://cdn.optimizely.com/js/18132920325.js"></script>
    <link rel="apple-touch-icon" sizes="57x57" href="/apple-icon-57x57.png">
    <link rel="apple-touch-icon" sizes="60x60" href="/apple-icon-60x60.png">
    <link rel="apple-touch-icon" sizes="72x72" href="/apple-icon-72x72.png">
    <link rel="apple-touch-icon" sizes="76x76" href="/apple-icon-76x76.png">
    <link rel="apple-touch-icon" sizes="114x114" href="/apple-icon-114x114.png">
    <link rel="apple-touch-icon" sizes="120x120" href="/apple-icon-120x120.png">
    <link rel="apple-touch-icon" sizes="144x144" href="/apple-icon-144x144.png">
    <link rel="apple-touch-icon" sizes="152x152" href="/apple-icon-152x152.png">
    <link rel="apple-touch-icon" sizes="180x180" href="/apple-icon-180x180.png">
    <link rel="icon" type="image/png" href="/favicon-32x32.png" sizes="32x32">
    <link rel="icon" type="image/png" href="/android-chrome-192x192.png" sizes="192x192">
    <link rel="icon" type="image/png" href="/favicon-96x96.png" sizes="96x96">
    <link rel="icon" type="image/png" href="/favicon-16x16.png" sizes="16x16">
    <link rel="manifest" href="/manifest.json">
    <meta name="apple-mobile-web-app-title" content="Elastic">
    <meta name="application-name" content="Elastic">
    <meta name="msapplication-TileColor" content="#ffffff">
    <meta name="msapplication-TileImage" content="/mstile-144x144.png">
    <meta name="theme-color" content="#ffffff">
    <meta name="naver-site-verification" content="936882c1853b701b3cef3721758d80535413dbfd">
    <meta name="yandex-verification" content="d8a47e95d0972434">
    <meta name="localized" content="true">
    <meta name="st:robots" content="follow,index">
    <meta property="og:image" content="https://www.elastic.co/static/images/elastic-logo-200.png">
    <link rel="shortcut icon" href="/favicon.ico" type="image/x-icon">
    <link rel="icon" href="/favicon.ico" type="image/x-icon">
    <link rel="apple-touch-icon-precomposed" sizes="64x64" href="/favicon_64x64_16bit.png">
    <link rel="apple-touch-icon-precomposed" sizes="32x32" href="/favicon_32x32.png">
    <link rel="apple-touch-icon-precomposed" sizes="16x16" href="/favicon_16x16.png">
    <!-- Give IE8 a fighting chance -->
    <!--[if lt IE 9]>
    <script src="https://oss.maxcdn.com/html5shiv/3.7.2/html5shiv.min.js"></script>
    <script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
    <![endif]-->
    <link rel="stylesheet" type="text/css" href="/guide/static/styles.css">
  </head>

  <!--© 2015-2021 Elasticsearch B.V. Copying, publishing and/or distributing without written permission is strictly prohibited.-->

  <body>
    <!-- Google Tag Manager -->
    <script>dataLayer = [];</script><noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-58RLH5" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
    <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start': new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0], j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src= '//www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f); })(window,document,'script','dataLayer','GTM-58RLH5');</script>
    <!-- End Google Tag Manager -->

    <!-- Global site tag (gtag.js) - Google Analytics -->
    <script async src="https://www.googletagmanager.com/gtag/js?id=UA-12395217-16"></script>
    <script>
      window.dataLayer = window.dataLayer || [];
      function gtag(){dataLayer.push(arguments);}
      gtag('js', new Date());
      gtag('config', 'UA-12395217-16');
    </script>

    <!--BEGIN QUALTRICS WEBSITE FEEDBACK SNIPPET-->
    <script type="text/javascript">
      (function(){var g=function(e,h,f,g){
      this.get=function(a){for(var a=a+"=",c=document.cookie.split(";"),b=0,e=c.length;b<e;b++){for(var d=c[b];" "==d.charAt(0);)d=d.substring(1,d.length);if(0==d.indexOf(a))return d.substring(a.length,d.length)}return null};
      this.set=function(a,c){var b="",b=new Date;b.setTime(b.getTime()+6048E5);b="; expires="+b.toGMTString();document.cookie=a+"="+c+b+"; path=/; "};
      this.check=function(){var a=this.get(f);if(a)a=a.split(":");else if(100!=e)"v"==h&&(e=Math.random()>=e/100?0:100),a=[h,e,0],this.set(f,a.join(":"));else return!0;var c=a[1];if(100==c)return!0;switch(a[0]){case "v":return!1;case "r":return c=a[2]%Math.floor(100/c),a[2]++,this.set(f,a.join(":")),!c}return!0};
      this.go=function(){if(this.check()){var a=document.createElement("script");a.type="text/javascript";a.src=g;document.body&&document.body.appendChild(a)}};
      this.start=function(){var a=this;window.addEventListener?window.addEventListener("load",function(){a.go()},!1):window.attachEvent&&window.attachEvent("onload",function(){a.go()})}};
      try{(new g(100,"r","QSI_S_ZN_emkP0oSe9Qrn7kF","https://znemkp0ose9qrn7kf-elastic.siteintercept.qualtrics.com/WRSiteInterceptEngine/?Q_ZID=ZN_emkP0oSe9Qrn7kF")).start()}catch(i){}})();
    </script><div id="ZN_emkP0oSe9Qrn7kF"><!--DO NOT REMOVE-CONTENTS PLACED HERE--></div>
    <!--END WEBSITE FEEDBACK SNIPPET-->

    <div id="elastic-nav" style="display:none;"></div>
    <script src="https://www.elastic.co/elastic-nav.js"></script>

    <!-- Subnav -->
    <div>
      <div>
        <div class="tertiary-nav d-none d-md-block">
          <div class="container">
            <div class="p-t-b-15 d-flex justify-content-between nav-container">
              <div class="breadcrum-wrapper"><span><a href="/guide/" style="font-size: 14px; font-weight: 600; color: #000;">Docs</a></span></div>
            </div>
          </div>
        </div>
      </div>
    </div>

    <div class="main-container">
      <section id="content">
        <div class="content-wrapper">

          <section id="guide" lang="en">
            <div class="container">
              <div class="row">
                <div class="col-xs-12 col-sm-8 col-md-8 guide-section">
                  <!-- start body -->
                  <div class="page_header">
<p>
  <strong>WARNING</strong>: The 2.x versions of Elasticsearch have passed their
  <a href="https://www.elastic.co/support/eol">EOL dates</a>. If you are running
  a 2.x version, we strongly advise you to upgrade.
</p>
<p>
  This documentation is no longer maintained and may be removed. For the latest
  information, see the <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/index.html">current
  Elasticsearch documentation</a>.
</p>
</div>
<div id="content">
<div class="breadcrumbs">
<span class="breadcrumb-link"><a href="index.html">Elasticsearch: The Definitive Guide [2.x]</a></span>
»
<span class="breadcrumb-link"><a href="languages.html">Dealing with Human Language</a></span>
»
<span class="breadcrumb-link"><a href="stopwords.html">Stopwords: Performance Versus Precision</a></span>
»
<span class="breadcrumb-node">Stopwords and Performance</span>
</div>
<div class="navheader">
<span class="prev">
<a href="using-stopwords.html">« Using Stopwords</a>
</span>
<span class="next">
<a href="common-terms.html">Divide and Conquer »</a>
</span>
</div>
<div class="section">
<div class="titlepage"><div><div>
<h2 class="title">
<a id="stopwords-performance"></a>Stopwords and Performance<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch-definitive-guide/edit/2.x/240_Stopwords/30_Stopwords_and_performance.asciidoc">edit</a>
</h2>
</div></div></div>
<p>The biggest disadvantage of keeping stopwords is that of performance. When
Elasticsearch performs a full-text search, it has to calculate the relevance
<code class="literal">_score</code> on all matching documents in order to return the top 10 matches.</p>
<p>While most words typically occur in much fewer than 0.1% of all documents, a
few words such as <code class="literal">the</code> may occur in almost all of them.  Imagine you have an
index of one million documents.  A query for <code class="literal">quick brown fox</code> may match  fewer
than 1,000 documents.  But a query for <code class="literal">the quick brown fox</code> has to score and
sort almost all of the one million documents in your index, just in order to
return the top 10!</p>
<p>The problem is that <code class="literal">the quick brown fox</code> is really a query for <code class="literal">the OR quick
OR brown OR fox</code>—any document that contains nothing more than the almost
meaningless term <code class="literal">the</code> is included in the result set.  What we need is a way of
reducing the number of documents that need to be scored.</p>
<div class="section">
<div class="titlepage"><div><div>
<h3 class="title">
<a id="stopwords-and"></a>and Operator<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch-definitive-guide/edit/2.x/240_Stopwords/30_Stopwords_and_performance.asciidoc">edit</a>
</h3>
</div></div></div>
<p>The easiest way to reduce the number of documents is simply to use the
<a class="xref" href="match-multi-word.html#match-improving-precision" title="Improving Precision"><code class="literal">and</code> operator</a> with the <code class="literal">match</code> query, in order
to make all words required.</p>
<p>A <code class="literal">match</code> query like this:</p>
<div class="pre_wrapper lang-json">
<pre class="programlisting prettyprint lang-json">{
    "match": {
        "text": {
            "query":    "the quick brown fox",
            "operator": "and"
        }
    }
}</pre>
</div>
<p>is rewritten as a <code class="literal">bool</code> query like this:</p>
<div class="pre_wrapper lang-json">
<pre class="programlisting prettyprint lang-json">{
    "bool": {
        "must": [
            { "term": { "text": "the" }},
            { "term": { "text": "quick" }},
            { "term": { "text": "brown" }},
            { "term": { "text": "fox" }}
        ]
    }
}</pre>
</div>
<p>The <code class="literal">bool</code> query is intelligent enough to execute each <code class="literal">term</code> query in the
optimal order—​it starts with the least frequent term.  Because all terms
are required, only documents that contain the least frequent term can possibly
match. Using the <code class="literal">and</code> operator greatly speeds up multiterm queries.</p>
</div>

<div class="section">
<div class="titlepage"><div><div>
<h3 class="title">
<a id="_minimum_should_match"></a>minimum_should_match<a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch-definitive-guide/edit/2.x/240_Stopwords/30_Stopwords_and_performance.asciidoc">edit</a>
</h3>
</div></div></div>
<p>In <a class="xref" href="match-multi-word.html#match-precision" title="Controlling Precision">Controlling Precision</a>, we discussed using the <code class="literal">minimum_should_match</code> operator
to trim the long tail of less-relevant results.  It is useful for this purpose
alone but, as a nice side effect, it offers a similar performance benefit to
the <code class="literal">and</code> operator:</p>
<div class="pre_wrapper lang-json">
<pre class="programlisting prettyprint lang-json">{
    "match": {
        "text": {
            "query": "the quick brown fox",
            "minimum_should_match": "75%"
        }
    }
}</pre>
</div>
<p>In this example, at least three out of the four terms must match. This means
that the only docs that need to be considered are those that contain either the least or second least frequent terms.</p>
<p>This offers a huge performance gain over a simple query with the default <code class="literal">or</code>
operator!  But we can do better yet…​</p>
</div>

</div>
<div class="navfooter">
<span class="prev">
<a href="using-stopwords.html">« Using Stopwords</a>
</span>
<span class="next">
<a href="common-terms.html">Divide and Conquer »</a>
</span>
</div>
</div>

                  <!-- end body -->
                </div>
                <div class="col-xs-12 col-sm-4 col-md-4" id="right_col">
                  <div id="rtpcontainer" style="display: block;">
                    <div class="mktg-promo">
                      <h3>Most Popular</h3>
                      <ul class="icons">
                        <li class="icon-elasticsearch-white"><a href="https://www.elastic.co/webinars/getting-started-elasticsearch?baymax=default&amp;elektra=docs&amp;storm=top-video">Get Started with Elasticsearch: Video</a></li>
                        <li class="icon-kibana-white"><a href="https://www.elastic.co/webinars/getting-started-kibana?baymax=default&amp;elektra=docs&amp;storm=top-video">Intro to Kibana: Video</a></li>
                        <li class="icon-logstash-white"><a href="https://www.elastic.co/webinars/introduction-elk-stack?baymax=default&amp;elektra=docs&amp;storm=top-video">ELK for Logs &amp; Metrics: Video</a></li>
                      </ul>
                    </div>
                  </div>
                </div>
              </div>
            </div>
          </section>

        </div>


<div id="elastic-footer"></div>
<script src="https://www.elastic.co/elastic-footer.js"></script>
<!-- Footer Section end-->

      </section>
    </div>

<script src="/guide/static/jquery.js"></script>
<script type="text/javascript" src="/guide/static/docs.js"></script>
<script type="text/javascript">
  window.initial_state = {}</script>
  </body>
</html>
